On Wednesday, XKCD creator Randall Munroe announced that he's written a book. Within 24 hours, the book — scheduled for a September release — was a bestseller on Amazon. So, as of now, he's only two places behind Rush Limbaugh's children's book starring "Rush Revere" and America:

The book itself is based off of Munroe's "What If" column, something of a side project to the XKCD comic where he makes illustrated answers to user-submitted questions. Appropriately, the published volume is called What If?: Serious Scientific Answers to Absurd Hypothetical Questions. It'll contain a mix of previous "what if" columns and new comics. "As I’ve sifted through the letters submitted to What If every week, I’ve occasionally set aside particularly neat questions that I wanted to spend a little more time on," Munroe explained in the book's announcement.

It's always hard to tell what advance interest like this will translate into when the release date comes — call it Snakes on a Plane syndrome, if you will. A blogger at "Beyond Black Friday," which first noticed Munroe's early bestseller status, speculated that the book's high position on Amazon's physical "books" bestseller, coupled with its absence from the Kindle e-books list, means "it’s much easier to get to the top of Amazon’s list of print best-sellers" because not that many people buy print books anymore. Although there's some truth to the idea that e-book sales have overtaken print sales, the highly visual nature of Munroe's upcoming book makes that assumption that its current bestseller status is misleading seems a bit premature. But whatever happens with "What If?" there's a precedent for beloved webcomic creators selling new books briskly out of the gate, thanks in part to their rabid Internet fanbase. Last fall, "Hyperbole and a Half's" Allie Brosh published her long-anticipated book, which quickly became a bestseller. The only issue is whether these Internet sensations can sustain their sales momentum once their biggest fans already stepped up.